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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.security;

import java.security.spec.AlgorithmParameterSpec;

/**
 * <p> This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
 * for the {@code KeyPairGenerator} class, which is used to generate
 * pairs of public and private keys.
 *
 * <p> All the abstract methods in this class must be implemented by each
 * cryptographic service provider who wishes to supply the implementation
 * of a key pair generator for a particular algorithm.
 *
 * <p> In case the client does not explicitly initialize the KeyPairGenerator
 * (via a call to an {@code initialize} method), each provider must
 * supply (and document) a default initialization.
 * For example, the <i>Sun</i> provider uses a default modulus size (keysize)
 * of 1024 bits.
 *
 * @author Benjamin Renaud
 * @see KeyPairGenerator
 * @see java.security.spec.AlgorithmParameterSpec
 */

public abstract class KeyPairGeneratorSpi {

  /**
   * Initializes the key pair generator for a certain keysize, using
   * the default parameter set.
   *
   * @param keysize the keysize. This is an algorithm-specific metric, such as modulus length,
   * specified in number of bits.
   * @param random the source of randomness for this generator.
   * @throws InvalidParameterException if the {@code keysize} is not supported by this
   * KeyPairGeneratorSpi object.
   */
  public abstract void initialize(int keysize, SecureRandom random);

  /**
   * Initializes the key pair generator using the specified parameter
   * set and user-provided source of randomness.
   *
   * <p>This concrete method has been added to this previously-defined
   * abstract class. (For backwards compatibility, it cannot be abstract.)
   * It may be overridden by a provider to initialize the key pair
   * generator. Such an override
   * is expected to throw an InvalidAlgorithmParameterException if
   * a parameter is inappropriate for this key pair generator.
   * If this method is not overridden, it always throws an
   * UnsupportedOperationException.
   *
   * @param params the parameter set used to generate the keys.
   * @param random the source of randomness for this generator.
   * @throws InvalidAlgorithmParameterException if the given parameters are inappropriate for this
   * key pair generator.
   * @since 1.2
   */
  public void initialize(AlgorithmParameterSpec params,
      SecureRandom random)
      throws InvalidAlgorithmParameterException {
    throw new UnsupportedOperationException();
  }

  /**
   * Generates a key pair. Unless an initialization method is called
   * using a KeyPairGenerator interface, algorithm-specific defaults
   * will be used. This will generate a new key pair every time it
   * is called.
   *
   * @return the newly generated {@code KeyPair}
   */
  public abstract KeyPair generateKeyPair();
}
